Active Bending Mechanism Employing Granular Jamming and Vacuum-Controlled Adaptable Gripper

Abstract

We propose a bending mechanism in this study capable of wrapping around objects of various shapes and increasing its stiffness simply via the evacuation of internal air. Unlike vacuum splints requiring manual wrapping and pneumatic bending devices based on granular jamming requiring a complicated combination of two separate air control systems, our proposed mechanism can wrap itself around objects using a single air evacuation system. An elastic container enveloping polystyrene foam beads and urethane sponges is employed in this mechanism. The compression of the sponges, caused by the evacuation of internal air, results in bending, while the stiffness of the mechanism increases simultaneously due to granular jamming. On embedding sponges having different stiffnesses, the resulting differences in the onset of sponge shrinkage cause sequential bending, which reduces the gaps between the mechanism and the target object. First, we developed a mattress-shaped bending mechanism that can be used as a vacuum splint and does not need to be manually wrapped around an object. Thereafter, an adaptable gripper was developed using the same bending mechanism. The gripper can wrap around objects having various shapes and increase its stiffness simply by evacuating internal air; it can even lift heavy objects.